You’ve heard other people say it, and maybe you’ve even uttered these words yourself: “Mutts are healthier than purebreds.” But is it really true?
As with most things, the answer isn’t so black and white. Cancer might be super common for some pure breed dogs (for example, 60% of golden retrievers die of it, which is more than twice the average rate for all breeds), while some mutts may enjoy a high quality of life well into their teens. Some studies that have compared purebreds to mixed breeds have found about a 10% increase in lifespan for comparably sized mixed-breed dogs. But what exactly makes mongrels more robust?
“Hybrid Vigor,” or “heterosity,” is a term that’s often used to explain the assumed “superior health” of mixed-breed dogs which is achieved by crossbreeding or outbreeding. If the offspring display characteristics superior to both parents, you’ve got a successful case of heterosity on your hands.
According to one hypothesis, heterosis occurs because of heterozygosity in crossbred offspring, which prevents pairs of damaging recessive alleles from matching up to cause defects and other health problems.
But there is, of course, one small catch. Outbreeding doesn’t automatically lead to heterosity. In fact, in some cases, the opposite, or “outbreeding depression,” can happen. For example, if a Basset Hound and a Mastiff were crossbred and the Basset passed on its long back while the Mastiff passed on its long legs and barrel chest, the resulting puppies would likely suffer from serious back problems. Generally speaking, close inbreeding is more detrimental than outbreeding or crossbreeding, but both types of breeding can have less than desirable results in terms of health and longevity.
It’s also worth noting that unlike with purebreds, most mutts don’t come from bloodlines where responsible breeders keep careful track of the health of every dog in the line. Purebreds may have more known health problems in their background, but sometimes this is only because better records have been kept.
Unfortunately there’s no foolproof way of predicting potential health problems for pooches. As with our own health, how well we fare often boils down to five main factors: environment, diet, our parent’s DNA, preventative maintenance and pure luck. That said, there are a few ways you can improve your chances of owning a healthy dog:
- If you are dead set on getting a purebred, carefully research and choose a breeder who does all possible health testing for the breed, and who will tell you honestly what hereditary defects are present in the lines that will produce your future pup. No line is ever perfectly healthy, so if a breeder tells you there are zero problems, walk away.
- If adopting a shelter dog, choose a pooch whose temperament, size and activity level match well with your family’s lifestyle. When you’ve identified a dog you think would be a good fit, ask the shelter if it has any information on the pups parents or health background. If you can, see if a vet that you trust can take a look at the dog before you adopt.
- Always practice good preventive care by taking your pet in for regular check ups; annual bloodwork can help detect organ failure early. Do your research and make informed decisions about diet and vaccinations. And be sure your pet gets plenty of exercise and love.